Level-shift type digital to analog converter

Abstract

This present invention relates to a level-shift type digital to analog converter including a selection circuit, a multiple voltage level generation circuit, a stabilization circuit and a level-shift type buffer stage circuit. The multiple voltage level generation circuit is composed by a divided-step voltage output circuit and a level voltage output circuit, for generating a plurality of voltage levels to directly output to a level-shift type buffer stage circuit or alternatively, to be processed through voltage selection in order to respectively output the divided-step voltage output values and the level voltage output values to a level-shift type buffer stage circuit. A stabilization circuit generates a reference voltage or a reference current insensitive to the power supply voltage V.sub.DD for other elements of the converter. Finally, the level-shift type buffer stage circuit synthesizes the received divided-step voltage and the level voltage, amplifies them with appropriate times and finally converts them to analog output signals.

Claims

1. A level-shift type digital-to-analog converter comprising:

(a) a selection circuit for converting original digital values to a plurality of digital codes for the digital-to-analog converter and then outputting the plurality of digital codes;

(b) a divided-step voltage output circuit connected to the selection circuit for receiving at least one of the plurality of the digital codes output from the selection circuit, and then outputting a voltage signal according to a predetermined number of steps and the voltage difference of each step;

(c) a level voltage output circuit connected to the selection circuit for receiving at least one of the plurality of digital codes output from the selection circuit, and then outputting a voltage signal according to a predetermined number of levels and the voltage difference of each level; and

(d) a level-shift type buffer stage circuit connected to the divided-step voltage output circuit and the level voltage output circuit, for receiving and processing the output signals from the divided-step voltage output circuit and the level voltage output circuit, and outputting an analog voltage output signal in demand.

2. The level-shift type digital-to-analog converter according to claim 1, wherein the product of the number of the steps of the divided-step voltage output circuit multiplying the number of the steps of the level voltage output circuit is the number of steps of the analog voltage output signal in demand.

3. The level-shift type digital-to-analog converter according to claim 1, wherein a combination of the divided-step voltage output circuit and the level voltage output circuit and the level-shift type buffer stage circuit including:

a divided-step current output circuit connected to the selection circuit for receiving at least one of the plurality of the digital codes from the selection circuit and outputting a current signal according to a predetermined number of steps and the current difference between each step;

a level current output circuit connected to the selection circuit for receiving at least one of the plurality of digital codes from the selection circuit and outputting a current signal according to a predetermined number of levels and the current difference between each step;

a current/voltage conversion circuit connected to the divided-step current output circuit and the level current output circuit for receiving the current signals therefrom and then converting the current signals to a voltage value for a final output.

4. The level-shift type digital-to-analog converter according to claim 3, wherein the product of the number of the steps of the divided-step current output circuit multiplying the number of the steps of the level current output circuit is the number of steps of the analog voltage output signal in demand.

5. The level-shift type digital-to-analog converter according to claim 3, further comprising a buffer stage circuit for receiving and processing the voltage signal output from the current/voltage conversion circuit, and then outputting the analog voltage output signal in demand.

6. A level-shift type digital-to-analog converter for receiving digital output signals and generating analog output signals in demand through divided-step voltage output values and a level voltage output value and incorporated a level-shift type buffer stage, the converter including:

a decoder for receiving the digital input signals and then converting the signals to a format receivable by a voltage selection circuit;

a voltage level selection circuit for receiving the signals from the decoder and a multi voltage level generation circuit, and outputting divided-step output voltage values and level voltage output values provided for a level shift type buffer stage circuit;

the multiple voltage level generation circuit for generating a plurality of voltage levels for voltage level selection; and

the level-shift type buffer stage circuit, for synthesizing the divided-step voltage and the level voltage from the voltage selection circuit and converting the synthesized signal to the analog output signal in demand.

7. The level-shift type digital-to-analog converter according to claim 6, wherein the multiple voltage level generation circuit is utilized for generating a plurality of voltages of different levels, and includes a serial circuit composed by a plurality of resistors in series, the two terminals of the resistors are connected between a high voltage level and a low voltage level.

8. The level-shift type digital-to-analog converter according to claim 6, wherein the voltage level selection circuit includes a plurality of switching elements controlled by the decoder so that the output terminals of the voltage level selection circuit respectively output appropriate amplitude s of divided-step voltage output values and the level voltage output values.

9. The level-shift type digital-to-analog converter according to claim 6, further including a stabilization circuit for generating at least a reference voltage or a reference current insensitive to the power supply voltage for providing to the circuit of the converter.

10. The level-shift type digital-to-analog converter according to claim 6, wherein the voltage level selection circuit includes a divided-step voltage selection circuit for outputting divided-step voltages and, a level voltage selection circuit for outputting the level voltage.